1. Field of the Invention
The disclosure described herein pertains to the field of computer printers configured to generate three dimensional objects from a computer data file. More particularly, but not by way of limitation, the disclosure provided here is directed to an imaging system and methods for generating three dimensional objects using an optical focusing system, sources of heat and simple motion systems.
2. Description of the Related Art
Solid imaging systems, including three dimensional (3D) printers and rapid prototyping (RP) systems, are primarily used to produce objects and prototype parts from 3D computer-aided design (CAD) tools. Most RP systems use an additive, layer-by-layer approach to building parts by joining liquid, powder, or sheet materials to form physical objects. The data referenced in order to create the layers is generated from a CAD system file using thin, horizontal cross-sections of the model. Typically, layers are constructed using a thin layer of a sinterable powder that is formable into a coherent mass through the application of heat. The prior art 3D printing systems that make use of heat to join the materials together generally employ high powered lasers and high precision motion systems containing a multitude of actuators to generate parts; resulting in a 3D printer which is generally not cost effective for the majority of home/hobbyist users or small mechanical design groups.
U.S. Pat. No. 7,261,542 describes a 3D printer system which does not require high powered lasers or high precision motion systems, which is hereby incorporated by reference in its entirety. This 3D printer system uses an incoherent energy source whose energy is focused to provide a small area of concentrated heat to generate layer-by-layer 3D printing.
In 3D printing involving sintering, the elevated temperatures required make implementation of cost effective optics problematic. Standard optical and electrical components and materials are designed for use within an operational temperature range. Furthermore, it has been found that, if a glass surface near a sintering surface dips close to the melting temperature of the sintering material, the glass surface collects a film of the material, limiting light transmission. Therefore, optics located near a sintering surface must be frequently checked for contaminants that might block light transmission and when necessary cleaned and maintained.
For at least the reasons described above there is a need for an optical imaging assembly for use within a 3D printer system that can generate a focused light for sintering without accumulating materials that reduce light transmission and without having expensive cooling systems or expensive optical elements in the high-temperature environment needed for sintering.